There are so many different types of flour, and different ways of measuring, that it is impossible to answer this question with any accuracy. Not only will the weight of a cup of flour vary depending on how it is scooped, or sifted, or poured into the cup, but the same flour will weigh more on a humid day because it absorbs moisture from the air.

People fill a cup with flour either by spooning, scooping, or dipping. All three methods will vary in the amount put in the cup. The general consensus is a cup of all purpose flour is between 4 and 5 ounces in weight. There are 16 weight ounces in a pound of flour. You will have anywhere between 3.2 and 4 cups in that pound of flour.